Physics

• Life Cycle of a Star

  Cloud of dust-- protostar-- main sequence star-- red giant or red super giant

  
  

  red giant-- white dwarf -- black dwarf

  
  

  red super giant-- supernova-- black hole or neutron star
• What is a Red Shift?

  An increase in wavelength, distant between galaxies and earth are expanding= UNIVERSE EXPANDING!
• Fleming Left Hand Rule


  FORCE =Magnetic Flux Density X Current X Length

  
• Right Hand Thumb Rule


  Shows magnetic field round a current and the way it flows

  
• What is the motor effect


  A current carrying conductor moves due to interacting with a magnetic field experiences a force
• Which of fleming's rule does the motor effect apply to?

  Fleming's Left Hand Rule
• What is the Generator Effect ?


  Induced potential difference ( and current if circuit connected) in a conductor moving through a magnetic field.
• Which Fleming's rule is used for the generator effect?

  Fleming's Right Hand Rule
• Loudspeakers use what effect?


  The Motor Effect
• National Grid 


  Power station-- step up transformer-- transmission cables-- step down transformers-- homes
• Transformers formula


  ratio of number of turns in coil= ratio of voltages

  
• What is ohms law?


  pd= current x resistance

  pd is proportional to current also as all over factors are constant
• current, pd, resistance in series circuit

  c= same everywhere

  pd= splits between each component

  r= adds up
• current, pd, resistance in parallel circuit


  c= splits down each branch

  pd= same down each branch

  r= lower than smallest resistance
• scalar vs vectors


  s= magnitude only

  v= magnitude and direction
• Newtons 3 laws


  1 a motion will remain at rest unless acted upon by an external force

  2 force = mass x acceleration

  3 every reaction has an opposite and equal reaction
• distance time graphs


  distance= speed x time

  
• Velocity time graphs


  acceleration = change in velocity / time

  
• contact vs non-contact forces

  c= friction, tension, air resistance

  nc= magnetic, electrostatic, gravitational
• dc vs ac


  dc= electrons only flow in 1 direction

  ac= electrons rapidly change direction (this is mains electricity)
• mains electricity= frequency and pd

  f= 50hz

  pd= 230v
• plug and different wires and fuse

  live wire (brown)= provides alternating pd from mains

  neutral wire (blue)= 0volts, carries away current

  earth wire (green/yellow)= safety, 0v, only carries current if a fault occurs, stops appliance casing from becoming live

  fuse= safety, if current is too high fuse breaks and cuts circuit
• Define current

  Rate of flow of electrons

  amps
• Define potential difference

  the amount of energy each electron is carrying

  volts
• Define power

  how much energy a device can transfer every second

  watts
• density

  d= m/v
• define latent heat


  specific latent heat of fusion of a substance is the energy needed to change the state of 1kg of a substance from solid to liquid at mp

  specific latent heat of vapourisation of a substance is the energy needed to change the state of 1kg of a substance from liquid to gas at bp
• Specific Heat Capacity


  the shc of a material is the amount of energy needed to heat 1kg of of a substance by 1c
• Heat curve


  solid-liquid-gas

  
• Transverse waves


  oscillations perpendicular to direction of energy transfer
• Longitundinal Waves


  Oscillations are parallel to direction of energy transfer
• examples of transverse


  em spectrum waves, ripples
• examples of longitundinal


  sound, ultrasound, shockwaves
• time period equation


  time period= 1/frequency
• wavespeed equation


  wavespeed= frequency x wavelength
• Electromagnetic Spectrum

  radiowaves--microwaves--infrared-visible light--ultraviolet--xrays--gamma rays

  frequency and energy increase from radiowaves to gamma rays

  wavelength decreases from radiowaves to gamma rays
• Uses of em waves


  radiowaves= communication

  microwaves= phones and microwaves

  infrared= thermal radiation

  visible light= 7 colours (what we see)

  ultra violet= produce vitamin D in sun and tanning beds

  X-rays= x-rays

  Gamma Rays= nuclear processes and kills cancer cells
• Define isotope


  atom of same elements with same number of protons but different number of neutrons
• Define ion


  Atoms that have gained or lost electrons
• radius of atom and nucleus


  atom = 1 x 10^-10m

  nucleus= 1x10^-15m